Report of Chesapeake Biological Laboratory R. V
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Report of Chesapeake Biological Laboratory, 1938 Item Type monograph Authors Truitt, R.V. Publisher Chesapeake Biological Laboratory Download date 25/09/2021 23:20:49 Link to Item http://hdl.handle.net/1834/28746 REPORT OF CHESAPEAKE BIOLOGICAL LABORATORY 1938 R. V. TRUITT* The program of work at the Chesapeake Biological Laboratory is being developed in a direction that will further the understand- ing of biological principles underlying conservation planning as well as to encourage the development of fundamental research. Efforts largely are centered in two directions, namely, research and teaching. Research problems are broad in their scope and many of them possess an important bearing on the preservation of natural resources in animal and plant life. Instructional work pertains to basic biology and to the status of natural resources as well as remedial measures that may assist in their development. Substantial progress was made in 1938 both in respect to additions made in the physical plant and to the problems effec- tively pursued by an energetic staff. The completion of a new and adequate building placed at the disposal of those working at Solmo- mons Island a greatly needed adjunct for the continuation of studies throughout the year. Much added equipment and space has been made available for the program being pursued, in the form of boats, technical apparatus, and added construction work for storage, Problems previously in course of study were continued dur- ing the current year, while new researches, in part economic and in part abstract, were initiated on Protozoa, on certain of the fin-fishes, and on new phases of the hydrography of the region. Certain of the previous investigations have been concluded. ORGANIZATION Six educational institutions manifested interest and gave sup- port to the work of the Laboratory: The Johns Hopkins Uni- versity, Western LVaryland College, Carnegie Institution of Wash- * Dr. Truitt is, Director of the Chesapeake Biological Laboratory dn Solomons Island, Professor of Zoology in the University of Maryland, and Biologist, Mlaryland Conservation Commission. ington, Goucher College, Washington College, and University of Maryland. The administration of the Laboratory's program is vested in an executive committee composed of representatives from the aforementioned institutions. Executive Committee : ROBERTF. DUEB, Conservation Com?nissioner, Chairman. DAVIDALLEN ROBERTSON,President, Gouclzer College. ISAIAH BOWMAN,President, Johtzs Hopkins University. H. CLIFTON BYRD, President, University of Maryland. FREDG. HOLLOWAY,President, Western Ma~ylandCollege. GILBERTWILCOX MEAD, President, Washington College. R. V. TRUITT,Director (ex-officio) . The teaching and research programs of the Laboratory are administered by a Committee on Investigation and Instruction, the members of which are listed below, with the names of the institutions they represent. Committee on Investigation and Instruction: R. V. TRUITT,PH. D., University of Maryland, Chai~man. PAULS. CONGER,M. S., Curnegie Institution of Washington. GAIRDNERB. MOMENT,PH. D., Goucher College. S. 0. MAST, PH. D., Johns Hopkins University. JULIAND. CORRINGTON,PH. I)., Washington College. LLOYDM. BERTHOLF,PH. D., Western Maryland College. Staff Members : The following named persons constituted the permanent staff of the Laboratory. A. A. BLAIR, PH. D., Assistant Fishery Biologist. A. G. LANG,PH. D., Associate Botanist. R. A. LITTLEFORD,PH. D., Associate Zoologist. J. H. MCLAIN, B. S., Assistant Chemist. HARVEYMISTER, Captain, In Charge of Boat. C. L. NEWCOMBE,PH. D., Ecologist, In Charge of Research. B. B. SHEPHERD,B. S., Research Assistant. R. V. TRUITT,PH. D., Biologist, Director, D. H. WALLACE,M. S. Assistant Fishery Biologist. GENERAL PROGRAM Teaching : The teaching program of the Laboratory followed, in the main, the established alignment of courses. The subjects offered have been selected to provide the student with an opportunity - for mastering basic biology and to acquire facts essential for understanding and contributing to the problems of conservation. As in the past, courses in Economic Zoology, Invertebrate Zoolcgy, and Biological Problems were offered. Due to unavoidable cir- cumstances, it was necessary to remove temporarily from the curriculum the course in Diatoms and that in Algae. The introduc- tion of a new course of study, Protozoology, has helped greatly to strengthen the program of teaching. A list of the courses 2nd the instructors offering same is given here: , Economic Zoology-Marcus C. Old, Ph.D.-Ursinus College. Invertebrate Zooiogy-Henry Olsen, Ph.D.-Wilson Teachers I College. Protozoolcgy-Richard Kudo, Ph.D.-University of Illinois. Experimental Zoology-Curtis L. Newcombe, Ph.D.-University of Maryland. Biological Problems-Staff. Researches of a more fundamental as well as applied charac- ter have been in progress on several of the more important Bay forms, and on the environmental factors governing their distri- bution and abundance. Thus special aspects of the biology of the Rock, Roccus lineatus, the Shad, Alosa sapidissima, the Croak- er, Micropogon undulatus, the Blue Crab, Callinectes sapidus. the Boring Sponge, Cliona celata, the Oyster, Ostrea uirginica, the Sea Nettle, Dactylometra quinquecirrha, the Snail, Littorina irrorata, the Clam, Venus mercenaria, and other forms have been investigated. Qualitative and quantitative s~udiesof the microscopic animal and plant life in the Bay waters, throughout the different seasons, are being continued. Information has been gathered on certain local fish and oyster parasites. Also, much attention has been given to the areas of the Bay in which there is destruction of life due to pollution. Other unfavorable environments that have received attention are the low oxygen water-layers occurring mar the bottom over extensive areas of the Bay. Fishes : ROCK OR STRIPED BASS. The program of investigation on the more important fishes was continued with the Rock, Roccus lineat us, and the Shad, Alosa sapidissirna, while added emphasis was given to the study of the Croaker, Micropogon undulatus, for which a detailed program of attack has been developed and initiated. To a limited extent both the Shad and the Croaker were tagged during the year. The return of tags, from some three thousand and five hundred Rock released in the fall of 1937, in Maryland, Virginia, and North Carolina, shows a marked decline as compared with like returns from fish tagged in 1936. Up to October 1, 1938, three hundred and thirty-five of the fish had been recaptured, that is, approximately ten per cent of the total number released. This decline in returns seems to indicate a lessened availability to the fisherman caused by the greatly reduced numbers of the fish of the 19 3 4 brood, which in 19 3 6 and 19 3 7 composed a "decidedly greater part of the catch. During the current year, very few recap- tures were reported from the fish released in 1936, no tags bzing returned during the last six months. This fact affords a strong indication that the method of tagging employed is not enti~ely satisfactory for experiments designed to yield data over a period of several years, although the results obtainsd have marked values for the first and even the second year after release, the period dur- ing which tags have been established to be durable, and the method employed efficient. Tagging operations during the 1937 season bear out pre- vious findings concerning out-of-Bay movements, in that five marked Rock migrated to other bodies of water. Two of these fish passed to northern waters, while one, marked in the James River, was recaptured in Albemarle Sound, North Carolina. The latter represented the first recapture of fish marked in the Chesapeake Bay from a point south of that body of water. Two North Carolina tagged fish were recaptured in New England waters. Tagging within Chesapeake proper, during 193 7, indicated movements in the main schools of Rock corresponding to those observed from previous tagging. However, the striking winter migrations of 1936 and 1937, from the upper Bay to the James River, were not repeated. Rather, the fish tended to remain in the deeper areas in the upper reaches of the Bay. Further informa- tion was gained from tags as to the migration routes to spawning grounds which are located, typically, just above the brackish water areas in the Bay and its tributaries. Many hundreds of observations were made on gonad devel- opment in the Rock in order to determine more definitely the season of spawning and the size and age at the time of sexual development. The peak of the spawning season is found to be about May 1. Females mature at approximately eighteen inches in Iength and in their fourth year of age, whereas the males mature while younger and at smaller sizes. BUILT-IN EXPERIMENTAL TANKS In order to determine the part the 1934 brood was playing in the catches of the various types of fishing gear, upward of five hundred measurements were made on Rock, which measurements afford data for the determination of the rate of growth as well. Tank experiments on food consumption and growth rate of this fish have been carried on since the summer of 1937. Fish hatched in 1937 have thriven under controlled conditions, and by Novem- ber, 1938, had reached an average length of eight and one-half inches, a size that compares most favorably with native fish in the open waters. These observations have demonstrated that the greatest quantity of food is consumed by the fish during Septem- ber and that the smallest quantity is consumed in January. Con- trolled feeding experiments apparently verify observations made on the winter food habits of this fish in nature in that food was consumed throughout the period of low temperatures. Collection and analysis of statistical data on the catches of Rock have been continued and expanded. Further analysis on pound net catches have corroborated the information derived from measurements of samples, in that they indicate a marked decline in the quantity of the 1934 brood.